Wry and obsessive DI Buchan is a cop on the edge. Suave and self-assured Jack Harvey is a best-selling crime novelist with the world at his feet. As Buchan probes a 100-year-old cold case, his investigation takes him on a journey into the Edinburgh's literary past that will cause him to question his very existence and set him on a collision course with his onetime friend [1]. DI Buchan often discuss with the spirit apparition of Arthur Conan Doyle.

The movie was commissioned as part of BBC Four's fifth birthday celebrations. The working title was The Acid Test. [2]